1. Field of the Invention
The present invention relates to a copper foil with both sides roughened, which has a protection film, for use in an inner layer circuit of a multi-layered printed circuit board.
2. Background Information
Methods of producing a copper-clad laminated board (hereinafter abbreviated as "CCLB") for a multi-layered printed circuit board (hereinafter abbreviated as "MLPCB") include press molding of a both-side roughened copper foil (hereinafter abbreviated as "BSRCF") placed on a single prepreg therewith, and press molding of BSRCFs placed on both sides of a lamination of multiple prepregs therewith. The roughening of a copper foil is performed to improve the bonding between the copper foil and the prepreg.
However a BSRCF has such a shortcoming that when it is pressed with a prepreg, fine ruggedness on the roughened surface of the copper foil, which is pressed with a press plate, are likely to be crushed.
To prevent the crushing of ruggedness on the surface of the BSRCF, a metal film such as a copper foil or aluminum foil, or a conventionally used organic film such as polypropylene, polyethylene terephthalate, polyethylene, triphenylpentene or Tedra (trade name of a resin film made by Du Pont) is placed between a press plate and a BSRCF at the time of press molding.
It is however a very troublesome job to laminate the mentioned metal film or organic film on the BSRCF before pressing them in a press molding step. In addition, when the above mentioned organic film is used, the property of separation from the press plate is bad, and when the film is separated from the BSRCF after the press molding, printing of the organic film on the surface of the copper foil would be seen on the electron microscopic level. This printing will have a bad effect upon the subsequent process.
Conventionally, BSRCFs are supplied in a roll or sheet form, so that the ruggedness on the roughened surface may be smashed or foreign matter may stick on the roughened surface, for example, when the BSRCF is cut, packed or transported.